Thermal Disconnect Assembly Using Eutectic Solder for IDG
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Solution Overview
Problem
Integrated drive generators (IDGs) in gas turbine engines face failures that lead to excessive temperatures, necessitating a mechanism to decouple the IDG from the mechanical input to prevent further failures and degradation.
Innovation Solution
A thermal disconnect assembly comprising an input shaft, an output shaft, eutectic solder, and a disconnect clutch, where the eutectic solder holds the output shaft in a coupled state and melts upon reaching a threshold temperature, causing the disconnect clutch to urge the output shaft into a decoupled state, thereby disconnecting the IDG from the input shaft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the IDG remains coupled to the input shaft during operation, then continuous power transmission is maintained, but failure conditions cause excessive temperatures and further degradation
Solution Approach 1:
The eutectic solder utilizes phase transition from solid to liquid at a specific melting point to automatically disconnect the output shaft from the input shaft when excessive temperature is detected, thereby preventing further damage to the IDG system
Solution Approach 2:
The eutectic solder acts as an intermediary thermal link between the input shaft and output shaft, maintaining the coupled state during normal operation through its solid phase, and automatically disconnecting when it melts due to excessive temperature, thus mediating the protective disconnection function
2Reliability
If a thermal disconnect mechanism is implemented, then protection against excessive temperature is achieved, but device complexity increases due to additional components
Solution Approach 1:
The eutectic solder provides self-service thermal protection by automatically melting at its characteristic melting point when excessive temperature is reached, thereby autonomously triggering the disconnect mechanism without requiring external sensors, control systems, or additional actuators
Solution Approach 2:
The protective thermal disconnect function is extracted from complex electronic control systems and implemented through the inherent physical property of the eutectic solder's phase transition, simplifying the overall device architecture by replacing complex control mechanisms with a passive thermal response
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively prevents further damage and degradation by ensuring the IDG is disconnected from the mechanical input when a failure occurs, maintaining system integrity and preventing additional failures.
Implementation Method 1
The eutectic solder is configured to hold the output shaft in the coupled state and melt upon reaching a threshold temperature
Data Source
Figure 1
Figure 2A
Figure 2B
AI summary
A thermal disconnect assembly (12) for an integrated drive generator includes an input shaft (14), an output shaft (30), a eutectic solder (36), and a disconnect clutch (38). The input shaft (14) is driven by an external mechanical source. The output shaft (30) is coupled to the input shaft (14) through a disconnect clutch (38) in a coupled state, is driven by the input shaft (14) and rotates with the input shaft (14) in the coupled state. The eutectic solder (36) is configured to hold the output shaft (30) in the coupled state and melt upon reaching a threshold temperature. The disconnect clutch (38) is configured to urge the output shaft (30) toward a decoupled state upon melting of the eutectic solder (36) such that the output shaft (30) does not rotate with the input shaft (14) in the decoupled state.